Art Shapiro's Butterfly Site

Arthur M. Shapiro, Center for Population Biology, UC Davis, Davis, CA 95616

This document is not copyrighted and may be circulated freely if properly credited. Last updated May 24, 2006.

Butterfly gardening in the foothills is different from butterfly gardening in California's Central Valley. In the Valley, most of the butterfly species are weedy, highly dispersive, multiple-brooded, reach highest densities in the autumn, and depend on a combination of introduced plants (weeds and cultivated species) and irrigation for their continued presence. In the foothills, though some of these weedy species still occur, most of the butterflies are native, adapted to the foothill climate, and thus restricted to one or two broods a year in spring, and less likely to feel at home in a garden. You have many more species nearby in the foothills, but may have a lot less action to see in your garden!

Your strategy and success gardening for butterflies in the foothills will depend heavily on your landscape surroundings.

Urban/Suburban

Most similar to butterfly gardening in the Valley, since most of the vegetation is “artificial.” Because winters are colder (and summers may be warmer, without the maritime influence below 1200 ft. near the San Francisco Delta), some of the weedy butterflies may be excluded, or may show up only late in the year and erratically (as overflow from the Valley). The farther you are from natural vegetation, the harder your job of attracting native species to the garden.

Ranchettes

Isolated homes on large lots often have quite a bit of grassland, with scattered native trees (mainly oaks; maybe Buckeye). The trees may sustain some butterfly populations, but much of the annual grassland is dominated by weeds not useful to butterflies; its fauna is likely to be poor. Rocky areas have richer native floras and more butterfly species; so do creek bottoms. Hog wallows (ephemeral ponds in low areas between hills) may have good plants but do not support special butterflies in our area. If your lot is dominated by Yellow Star Thistle (condolences!), it is a superb nectar source and will intercept virtually everything before it reaches your garden.

Semi-Natural

Where homes are interdigitated into more-or-less-intact landscapes, gardeners can tap into the resident fauna, whatever it is. There are few resident butterflies in closed-canopy forest. Most occur in clearings, along roads, and by streams. The highest diversity in our area always occurs on rocky canyon walls with a high diversity of flowering plants. Typically, streams that flow east-west have richer butterfly faunas than those that flow north-south because there is a greater climatic and vegetational difference between north- and south-facing slopes and each plant community brings its own fauna. If you live in or near such a canyon you may see from 40 to 70 species close to home! If you live on a special soil (serpentine, gabbro, limestone) you may have lower overall diversity but get special species not found anywhere else – things like John Muir’s Hairstrea, Mitoura muiri, that feeds on MacNab and Sargent Cypresses, or the Sleepy Duskywing (Erynnis brizo lacustra) that feeds on Leather Oak.

With so many different local situations to take into account, gardening hints for the foothills can only scratch the surface. Keep the following in mind:

• Few butterfly species can maintain an ongoing population within the confines of a residential lot – even a big one. If you get breeding, it will be as part of a larger “metapopulation” whose borders are constantly changing. Remember that an ongoing population requires larval host plants, pupation sites, adult food supply, and mating sites (which often means territories for males). Or just plain good juju.
• The principal function of a butterfly garden is to intercept individual butterflies as they move through an area and detain them where they can be observed and enjoyed. Occasionally, one can actually boost numbers by planting nectar sources or larval hosts, but only if these are otherwise in short supply. More often, one is just moving individuals around from one place to another.
• Valuable natural history data can be obtained from a butterfly garden.
• Skilful planting will enable you to maximize both the number of individuals and the number of species you see, but be realistic in your expectations: don’t expect endangered species to breed in your back yard.

Suggestions for Foothill Butterfly Gardens (by intended function)

Larval Host Plants for Native Butterflies

1. California Pipevine or Dutchman’s Pipe (Aristolochia californica): sole larval host of the Pipevine Swallowtail (Battus philenor).
2. Bush Monkey Flower (Mimulus or Diplacus aurantiacus); shrubby and perennial Penstemon and Keckiella; Bee Plant (Scrophularia): hosts of the Chalcedon or Variable Checkerspot (Euphydryas chalcedona). All of these plus Lippia, Plantains (Plantago), and garden Snapdragon are also hosts of the Buckeye (Junonia coenia).
3. Pearly and other Everlastings (Gnaphalium, Antennaria, Anaphalis): West Virginia Lady (Vanessa virginiensis).
4. Wild Buckwheats (Eriogonum species): All perennial and shrubby species are worth a try, though the large chaparral species from southern California are unlikely to be used. Wild Buckwheats serve as both hosts and nectar sources for several species of Blues, Coppers and Hairstreaks and the Mormon Metalmark (Apodemia mormo).
5. Native perennial vetches and sweetpeas (Vicia and Lathyrus, but NOT the introduced day-glo pink L. latifolius) and most perennial and shrubby Lupines, including the common Bush Lupine (Lupinus albifrons), are hosts for several Blues, some Hairstreaks, and the Northern Cloudy-Wing (Thorybes pylades).
6. Milkweeds (Asclepias, all species): Monarch (Danaus plexippus).
7. Native members of the Carrot Family, Apiaceae (Umbelliferae), including Biscuitroot (Lomatium); Angelica; Tauschia; Yampah (Perideridia), etc., as well as naturalized species such as Sweet Fennel or “anise” (Foeniculum vulgare), Poison Hemlock (Conium maculatum), Wild Carrot (Daucus carota): Anise Swallowtail (Papilio zelicaon).
8. Wild Lilacs (Ceanothus, all species): California Tortoiseshell (Nymphalis californica), Echo Blue (Celastrina ladon echo), Sepia Hairstreak (Satyrium saepium), Grinnell’s Duskywing (Erynnis pacuvius), Pale Swallowtail (Papilio eurymedon) (Papilio eurymedon – also eats Coffeberry, Rhamnus).
9. Deer Weed (Lotus scoparius); other Lotus, both annual (e.g. L. purshianus) and perennial (L. crassifolius, L. corniculatus): Eastern Tailed Blue (Everes comyntas), Acmon Blue (Plebejus acmon), Persius Duskywing (Erynnis persius), Northern Cloudy-Wing (Thorybes pylades), Silver-Spotted Skipper (Epargyreus clarus) —the last two only on L. crassifolius.
10. California Wild Indigo or Lead Plant, Amorpha californica and other Amorpha species: California Dogface (Zerene eurydice) , our State Insect. The Silver-Spotted Skipper (Epargyreus clarus) also breeds on Wild Indigo and on the introduced Black and New Mexico Locust (Robinia species).
11. Willows (Salix species, EXCEPT Weeping Willow, S. babilonica): Lorquin’s Admiral (Limenitis lorquini), and Willow Hairstreak (Satyrium sylvinus). The Mourning Cloak (Nymphalis antiopa) accepts Weeping Willow as well, along with soft-leaved species of Elm and Hackberry.
12. Oaks (Quercus, all, including exotic species): California Sister (Adelpha bredowii), California and Gold-Hunter’s Hairstreaks (Satyrium californica and S. auretorum), Propertius and Sad or Mournful Duskywings (Erynnis propertius and E. tristis). The Golden Oak Hairstreak (Habrodais grunus) uses only Quercus chrysolepis, although chinquapin (Chrysolepis chrysophylla) is used in Oregon.
13. Stinging Nettle (Urtica): Satyr Anglewing (Polygonia satyrus), Red Admiral (Vanessa atalanta), West Coast Lady (Vanessa annabella), Milbert's Tortoiseshell (Nymphalis milberti).

Other butterfly hosts worth trying are: